Question : Find the unit vector perpendicular to the plane of two vectors and ,

and

Oct 25th 2009, 12:34 AM

earboth

Quote:

Originally Posted by zorro

Question : Find the unit vector perpendicular to the plane of two vectors and ,

and

Use the formula:

Dec 22nd 2009, 02:06 AM

zorro

Is this correct?

Quote:

Originally Posted by earboth

Use the formula:

= =

= = =

= = ..............Is this correct ??

Dec 22nd 2009, 03:24 AM

mr fantastic

Quote:

Originally Posted by zorro

= = Mr F says: Correct.

= = = Mr F says: Correct.

= = ..............Is this correct ?? Mr F says: No.

You divided by 5. You're meant to divide by .

Dec 22nd 2009, 01:58 PM

zorro

okay

Quote:

Originally Posted by mr fantastic

You divided by 5. You're meant to divide by .

The result should be then

Dec 22nd 2009, 02:14 PM

Plato

Quote:

Originally Posted by zorro

The result should be then

Well it should be written as:

Dec 22nd 2009, 09:48 PM

zorro

Could u please explain

Quote:

Originally Posted by Plato

Well it should be written as:

Could u please explain how u got this answer.......

Dec 23rd 2009, 02:13 AM

mr fantastic

Quote:

Originally Posted by zorro

Could u please explain how u got this answer.......

Basic arithmetic. Cancel the common factor of 5.

Dec 23rd 2009, 02:15 AM

zorro

how did u get at the denominator

Dec 23rd 2009, 02:18 AM

mr fantastic

Quote:

Originally Posted by zorro

how did u get at the denominator

(you must have been taught how to rationalise the denominator of surds ....?)

Dec 23rd 2009, 02:26 AM

zorro

Quote:

Originally Posted by mr fantastic

(you must have been taught how to rationalise the denominator of surds ....?)

okay but is that neccessary ..........my answer is correct isnt it??

Dec 23rd 2009, 02:30 AM

mr fantastic

Quote:

Originally Posted by zorro

okay but is that neccessary ..........my answer is correct isnt it??

Yes, it is. But whether or not it got full marks would depend on whether the person marking it wanted a simplified answer. Certainly at this level the common factor of 5 should be cancelled. It is personal taste whether or not to rationalise the denominator. You should discuss this further with your instructor.